Process for preparing bis-(4-hydroxy-3,5-dialkylbenzyl) carboxylic acid esters

ABSTRACT

The reaction of one mole of a Mannich base corresponding to the formula   AND ONE MOLE OF A Mannich base corresponding to the formula   WHEREIN R1, R2, R4 and R5 are independently selected from alkyl groups having one to six carbon atoms and R is alkyl, preferably lower alkyl, with 1 mole of a carboxylic acid ester corresponding to the formula R3CH2COOR4 wherein R3 is -H, -CN or -COOR4 and R4 is an alkyl, thioethers oxyether or aralkyl group having up to 20 carbons in the presence of a catalytically effective amount of an alkaline catalyst is useful for preparing compounds corresponding to the formula   The compounds represented by the above formula are useful as stabilizers for synthetic resins, particularly polyolefins. Compounds of the above formula, when R3 is -CN are novel and may also be prepared by reacting 1 mole of   AND 1 MOLE   WHEREIN X is halogen with 1 mole of NCCH2COOR4 in the presence of an alkali metal and an anhydrous inert organic solvent.

lljnlteel tat ll [1 lEggensperger et al.

[ PROCESS FUR PREPARHNG BlS-(ll-HYDROXY-3,5-DHALKYLBENZYL) CARBQXYLIC ACHD lESTEllS [75] Inventors: llleinz lEggensperger, Bensheim;

Vollrer Franzen, Heidelberg; Karl-Heinz Dielil; Wilfred Kloss, both of Bensheim, all of Germany [73] Assignee: Ciba-Geigy Marienberg Gmbll-l,

Postfach, Germany 22 Filed: Dec. 22, 1971 21 App]. No.: 211,125

Related US. Application Data [63] Continuation-in-part of Ser. No. 714,!00, March 18,

1968, Pat. NO. 3,646,110.

[30] Foreign Application Priority Data Primary Examiner-Gotts Lewis Assistant Examiner-Dolph A. Torrence Attorney, Agent, or Ft'rmFisher, Christen & Sabol 5 7 ABSTRACT The reaction of one mole of a Mannich base corresponding to the formula 2 and one mole of a Mannich base corresponding to the formula [111 fifiaan [4 1 Dec. 2a, 1am

wherein R R R and R are independently selected from alkyl groups having one to six carbon atoms and R is alkyl, preferably lower alkyl, with 1 mole of a carboxylic acid ester corresponding to the formula R CH COOR wherein R is -l-l, -CN or COOR, and R is an alkyl, thioethers oxyether or aralkyl group having up to 20 carbons in the presence of a catalytically effective amount of an alkaline catalyst is useful for preparing compounds corresponding to the formula C COOR4 The compounds represented by the above formula are useful as stabilizers for synthetic resins, particularly polyolefins. Compounds of the above formula, when R is CN are novel and may also be prepared by reacting 1 mole of no- -CH2X and 1 mole of R5 ['10- -CH X wherein X is halogen with 1 mole of NCCH COOR in the presence of an alkali metal and an anhydrous inert organic solvent.

17 Claims, N0 Drawings ll 2 v PRO CESS FOR PREPARING R is preferably lower alkyl in the presence of a catalytic D QXY'32 ALK LBE amount of an alkaline compound selected from alkali CARBOXYLIC ACID ESTERS metal compounds and alkaline earth metal compounds. This invention relates to a novel process of preparing Wh R i th s m 35 R and R is the same as R,,, the

dlalkyl benlyl F lf i esters, Certain novel reaction may be conducted in a single step by reacting p l resms stablllledl two moles of the Mannich base with one mole of the l pp f l' a 'p f of our carboxylic acid ester. Suitable alkaline compounds in- Pendmg apphcatlon 714,100 filed clude the oxides, hydroxides, amides, hydrides and al- 1968 now 3,646,110 coholates of alkali and alkaline earth metals such as, Esters Ofthe formula lithium, sodium, potassium, calcium, magnesium and barium. Specific examples of suitable compounds in- R clude lithium, sodium and barium oxides; sodium, potassium, calcium, magnesium and barium hydrides; sodium, lithium, calcium, magnesium, and barium hydrides; sodium amide, sodium acetamide, lithium amide and magnesium amide; and sodium methylate, sodium ethylate, sodium propylate, sodium phenate, potassium phenate, calcium ethylate, magnesium meth- R ylate, magnesium ethylate and barium ethylate as well as mixtures thereof.

The Mannich bases react almost quantitatively with v the carboxylic acid esters and the Mannich bases are readily prepared by the well known reaction of phenols, formaldehyde, and secondary amines, such as dimethylamme. Therefore, this process of the present tnventlon provides a very economic procedure.

A preferred method for the preparation of symmetri- I cal bis-products from Mannich bases consists in reflux- 6 ing two moles of a Mannich base when R is the same as R and R is the same as R with 1 mole of carboxylic Wherem 1, 2 5 and s are the same or dlfferem acid ester (malonic acid ester, cyanoacetic acid ester) ear or branched alkyl groups having 1 to 6 Carbon at 60 to 250C. in the presence of l to 20 g of an alkali C-- COOR atomsi 3 is "-H 0T 4 and 4 is a metal or alkaline earth metal alcholate in a suitable sola branched, y es u a unsaturated alkyl, vent, e.g., in 1 liter of toluene, under nitrogen for /2 to thioether, ether, or aralkyl group, having I to 20 car- 4 hours. When the reaction is terminated, the reaction bon atoms can be prepared by reacting in an inert O mixture is cooled and the reaction product is recovgani s lvent one mole of a Mannich base of the f rered. For this purpose, the catalyst is first removed, mula e.g., by neutralization with dilute acid and shaking out 40 with water, and then the reaction solution is dried. The solvent is distilled off under reduced pressure and the residue may be purified by recrystallization. The yield is generally about 80 to 99 percent.

CHZN (R) 2 In the preparation of the asymmetrical bis-products, i which are particularly effective stabilizers, one mole of (III) carboxylic acid ester is reacted with one mole of a Mannich base according to the following'equation to and one mole of a Mannich base of the formula form an intermediate compound R1 i R1 This compound is then further reacted with one mole ofa Mannich base having different alkyl group than the first Mannich base to form the product. Both reactions can be carried out in the same reaction vessel similar to the procedure described above for the preparation of the symmetrical compounds. In the case ofthe asym- R5 (IV) metrical compounds, the two Mannich bases are added to the reaction vessel successively for refluxing wherein R R R and R are as defined above with one whereby the second Mannich base is generally added mole of a carboxylic acid ester of the formula R, CH about 2 hours after h fi base- 'COOR wherein R and R are as defined above and The reaction here involved is a C-alkylation" of the HO- cn n (R) 2 phenol Mannich bases to disubstituted malonic acid or cyanoacetic acid esters. The literature indicated that such C-alkylation would be possible only when the difficulty available ammonium salts of the phenol- Mannich base are used as starting material (see H. Hellmann and G. Opitz,a-Aminoalkylation, 1960, p. 284). It was not to be expected that the reaction described herein would be possible and would smoothly produce the novel malonic and cyanoacetic esters of the phenol Mannich bases.

The bis-(4-hydroxy-3,5 -dialkyl-benzyl) monocarboxylic ester compounds of formula I, wherein R =H, are obtained by saponification and decarboxylation of the corresponding cyanoacetic or malonic acid esters.

Compounds of the formula wherein R R R R and R are as defined above are novel. These compounds may be prepared by the novel process described above or can be prepared by reacting, in the presence of an anhydrous inert organic solvent and an alkali metal. 1 mole of HO -CH X and 1 mole of HO- EXAMPLE 1 PREPARATION OF BIS-(3,5-DI-TERT. BUTYL 4-HYDROXYBENZYL) CYANOACETIC ACID ETI-IYL ESTER.

A. 263.4 g (1 mole) of (4-hydroxy-3,5-di-tert.butylbenzy1)dimethylamine, 51 g (0.45 moles) of cyanoacetic acid ethylester, 3 g of magnesium ethylate, and 5 g of sodium methylate were refluxed in 1 liter of absolute alcohol for 1.5 hours; after cooling, the precipitated reaction product was filtered. The reaction product was shaken out with 96% alcohol and once recrystallized from 1.5 liter of acetone.

Yield: 255 g (99% of theory) M 212-213C Analysis: found: C 76.3% H 9.13% calc. C 76.37! H 9.357:

b. 300 g (1 mole) of 3,5-di-tert-butyl-4-hydroxybenzyl bromide and 56 g (0.5 moles) of cyanoacetic acid ethyl ester in 500 CC of petroleum other were added to a suspension of 23 g (1 g atom) of sodium in 1600 CC of petroleum ether with stirring and the mixture was refluxed for about 3 hours.

The reaction solution was then washed with water and dried. the solvent was evaporated under vacuum and the product was recrystallized from petroleum ether.

EXAMPLE 2 PREPARATION OF BIS-(4-HYDROXY-3-METHYL-5-TERT. BUTYLBENZYL) MALONIC ACID DISTEARYL ESTER.

(STABILIZER I) 27.6 g (0.125 mole) of (4-hydroxy-3-methyl-5-tert. butylbenzyl) dimethylamine, 30.5 g (0.05 mole) ofmalonic acid distearyl ester, and 0.5 g of sodium methylate were refluxed in 100 cc of absolute toluene for 2% hours while a current of nitrogen was passed through the reaction mixture. After cooling. the reaction mixture was diluted with methylene chloride, shaken out with 2N hydrochloric acid and water, and evaporated to dryness. the residue was slurried in methanol, fi1- tered, and washed.

Yield: 41 g of theory) m 83-90C Analysis: calc; C 78.69%; H 11.3271; 0 9.98% Found 2 C 79.25%; H 10.6671; 0 9.997!

This reaction also proceeds as described above with substantially the same yields if hydroxides such as so dium or potassium hydroxide; hydrides such as lithium, calcium or magnesium hydride or amides such as sodium or magnesium amide are used instead of the alcoholate.

EXAMPLE 3 PREPARATION OF 1-(3-METHYL-5-TERT.BUTYL-4-HYDROXY- PHENYL)-3-(3,5 -DI-ISOPROPYL-4-HYDROXYPHENYL )-2,2 -BlS-CARBOSTEAROXY PROPANE.

4.4g (0.02 mole) of (4-hydroxy-3-methyl- 5tert.butylbenzyl)-dimethylamine, 12.2 g (0.02 mole) Analysis: Calc.: C 78.7971; H 11.37%; 0 9.84% Found: C 78.72%; H 11.09%; 0 9.90%

EXAMPLE 4 PREPARATION OF BIS-( 3 ,S-DI-TERTBUTYL-4-HYDROXYBENZYL MALONlC ACID-DH 3-HEXYL-MERCAPTO)- PROPYLESTER.

(Stabilizer 11) By reaction of the Mannich base of 2,6di-tert.butyl phenol with malonic acid di(3-hexyl-mercapto) propyl ester, 23 g (0.055 mole) 'of malonic acid di(3-hexylmercapto) propyl ester, 32.8 g. (0.125 mole) of the TABLE I 6 Mannich base of 2,5-ditertiary butylphenol, and 0.5 g of sodium methylate were refluxed in 100 cc of absolute toluene for 1.5 hours, and, after cooling, washed with 2N hydrochloric acid, dried and concentrated to dryness. The residue was twice recrystallized from petrol ether.

Yield 369 g 80% of theory Analysis: Cale; c 73.08% H 7.82% 0 11.45%; s 7.05% Found: c 7270;11 8.03%; 0 11.22%; s 7477. MR 84-86C.

Some of the compounds prepared in an analogous manner, are: bis-(3,5-di-tert.butyl-4-hydroxybenzyl) malonic acid. di(3-laurylmercapto) propyl ester (Stabilizer III); m 7173C; yield 70%; a-(4-hydroxy-3,5-ditert.butylbenzyl)-a"-(4-hydroxy-3-tert.butyl-5methylbenzyl)-malonic acid distearyl ester (Stabilizer 1V)m 8790C; yield 81%.

Examples of other compounds which are prepared in the same way are listed in Table l, where they are defined by their substituents according to formula 1. Their structure, canbe determined, by their molecular weight, IR spectra, and quantitative analysis. The melting points of some specific compounds are also given vin degrees C. Under the column M.P. Those'compounds in which the R group is followed by a number in parenthesis are used in tests of other examples and are identified by this number.

-cn -ca CH3 -ca -c1-z -ca -coo1R 1. 1- n -c -c H 197-199 -cooR 192 1- -CN/ -CH2 (CH3) 2 -coon -CO0R4 1. u --cu -C (CH3) 3 -coon 1 -CN -CH2CH (CH3) 2 u -cooR u 1. H -ACN C6 H1 3 

1. A PROCESS FOR PREPARING BIS-(4-HYDROXY-3,5DIALKYLBENZYL) CARBOXYLIC ACID ESTERS HAVING THE FORMULA
 2. The process of claim 1 wherein said alkaline compound is selected from the group consisting of hydroxides, oxides, hydrides, amides and alcoholates.
 3. The process of claim 2 wherein R3 is -COOR4 and R4 is alkyl.
 4. The process of claim 2 wherein R3 is -CN and R4 is alkyl.
 5. The process of claim 2 wherein R3 is -COOR4 and R4 is sulfur interrupted alkyl.
 6. The process of claim 5 wherein said sulfur interrupted alkyl has more than one -S-.
 7. The process of claim 2 wherein R3 is -CN and R4 is an oxygen interrupted alkyl.
 8. The process of claim 2 wherein R3 is -COOR4 and R4 is aralkyl.
 9. The process of claim 2 wherein R3 is -CN and R4 is aralkyl.
 10. The process of claim 2 wherein R1, R2, R3 and R4 are t.butyl and said alkaline compound is an alcoholate.
 11. The process of claim 2 wherein R3 is COOR4 and R4 is oxygen interrupted alkyl.
 12. The process of claim 11 wherein said oxygen interrupted alkyl contains more than one -O-.
 13. The process of claim 7 wherein said oxygen interrupted alkyl contains more than one -o-.
 14. The process of claim 2 wherein R3 is COOR4 and R4 alkenyl.
 15. The process of claim 2 wherein R3 -CN and R4 alkenyl.
 16. The process of claim 2 wherein R3 is -CN and R4 is sulfur interrupted alkyl.
 17. The process of claim 16 wherein said sulfur interrupted alkyl has more than one -S-. 